ca ex s2m02 static routing

8/3/2019 CA Ex S2M02 Static Routing

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Chapter 2 - Static Routing

CCNA Ex loration 4.0

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Objectives

• Define the general role a router plays in networks.

• Describe the directly connected networks, different router

interfaces• Examine directly connected networks in the routing table

and use the CDP protocol

Hc vin mng Bach Khoa - Website: www.bkacad.com 2

• Describe summary and default route

• Examine how packets get forwarded when using staticroutes

• Identify how to manage and troubleshoot static routes



Labs




Routers and Network




Role of the Router

• The router is a special-purpose computer that plays a key role in theoperation of any data network.

• Routers are primarily responsible for interconnecting networks by:

1. Determining the best path to send packets

2. Forwarding packets toward their destination




Introducing the topology

• Topology Lab




Reference: Cisco router 1841’s Component

Product Description Quantity

CISCO1841Modular Router w/2xFE, 2 WAN slots, 32FL/128 DR 1

CAB-ACE Power Cord Europe 1

S184IPB-12406T Cisco 1841 IOS IP BASE W/O CRYPTO 1


WIC-2T 2-Port Serial WAN Interface Card 1

CAB-SS-V35FCV.35 Cable, DCE Female to Smart Serial, 10Feet 2

CAB-SS-V35MT V.35 Cable, DTE Male to Smart Serial, 10 Feet 2

MEM1800-32CF 32MB Cisco 1800 Compact Flash 1

ROUTER-SDM-CD CD for SDM software 1

CON-OSP-CISCO1841 ONSITE 24X7X4 Modular Router w/2xF 1



Cable Standards




Cable for LAN/WAN interfaces




Examining the Connections of the Router


• Serial Connectors – DB-60 port and Smart port: five-in-one serial port:

• EIA/TIA-232, EIA/TIA-449, V.35, X.21, and EIA/TIA-530standards



Examining the Connections of the Router


• Ethernet Connectors – 2 types of connectors can be used: Straight through and Cross-over Straight through used to connect:

• Switch-to-Router, Switch-to-PC, Router-to-Server, Hub-to-PC, Hub-to-Server Cross-over used to connect:

• Switch-to-Switch, PC-to-PC, Switch-to-Hub, Hub-to-Hub, Router-to-Router



Router Configuration Review




Examining Router Interfaces

• Examining Router Interfaces

– show ip route command – used to view routing table

– show interfaces command – used to show status of an interface

– show ip interface brief command – used to show a portion of theinterface information

– show running-config command – used to show configuration file




Configuring an Ethernet Interface

• Configuring an Ethernet interface

– By default all serial and Ethernet interfaces are down

– To enable an interface use the no shutdown command





• Verifying Ethernet interface

– Show interfaces for fastEthernet 0/0 – command used to showstatus of fast Ethernet port

– show ip interface brief

– show running-config

• Ethernet interfaces participate in ARP





• The IOS will return the following error message if youattempt to configure the second interface with thesame IP subnet as the first interface:

R1(config-if)#int fa0/1


- . . . . . .

172.16.3.0 overlaps with FastEthernet0/0

R1(config-if)#



Extra: Testing using the OSI Model




Logging Synchronous Command

• In order to keep the unsolicited output separate from your input,enter line configuration mode for the consoled port and add the

logging synchronous command.




Configuring a Serial Interfaces

• Configuring a Serial interface

– Enter interface configuration mode

– Enter in the ip address and subnet mask

– Enter in the no shut down command

• Example:

– R1(config)#interface serial 0/0


– con g- p a ress . . . . . .

– R1(config-if)#no shutdown




• Activity 2.2.5.1

• Examining Router Interfaces

– Physically connecting a WAN Interface.

– A WAN Physical Layer connection has sides:

- –


This is the service provider. CSU/DSU is a DCEdevice.

Data Terminal Equipment (DTE) – Typically the

router is the DTE device.





• on gur ng ser a n s n a a env ronmen One side of a serial connection must be considered a DCE This requires placing a clocking signal – use the clock rate

command. Example:

• R1(config)#interface serial 0/0• R1(config-if)#clockrate 64000 Serial Interfaces require a clock signal to control the timing of

the communications.

• Note: WIC-2a/s support maximum clock rate is 128000 bps



Extra: Clock Rate

RouterB(config)#inter serial 1

RouterB(config-if)#clock rate ?


pee s per secon

12002400

4800

9600

<text omitted>

2000000

4000000

<300-4000000> Choose clockrate from list above

RouterB(config-if)#clock rate 64000

RouterB(config-if)#




• Verifying the Serial Interface Configuration

– show interfaces

– show ip interface brief – show running-config

– ping

–




Verifying Changes to the Routing Table

• The routing table consists of a list of "known" network addresses- that is, those addresses that are directly connected, configured

statically, and learned dynamically.




Verifying Changes to the Routing Table

• Observing Routes as They are Added to the Routing Table

– debug ip routing command will let us see any changes that

the router performs when adding or removing routes.




Devices on Directly Connected Networks

• When a router only has its interfaces configured, and the routingtable contains the directly connected networks but no other

routes, only devices on those directly connected networks are

reachable.




Devices on Directly Connected Networks




Extra: Directly Connected Networks and the IP Routing Table

RTA# debug ip routing

RTA(config)#inter e 0

RTA(config-if)#shutdown

00:34:38: RT: interface Ethernet0 removed from routing table

00:34:38: RT: del 192.168.2.0 via 0.0.0.0, connected metric [0/0]

00:34:38: RT: delete network route to 192.168.2.0

RTA#show ip route

-


• Viewing the Routing Table Process

– Directly connected routes will also be removed if the link goes down. – Directly connected routes will only be in the routing table if, it is not

administratively down, the line is “up” and protocol is “up”

– For serial interfaces, don’t forget the “clock rate” command on the routerwith the DCE cable – neither interface will be “up” and “up” until both ends

are configured correctly.

,..

RTA# undebug all



Extra: Directly Connected Networks and the IP Routing Table

RTA#show ip routeCodes: C - connected,.. <Other codes and gateway information omitted>

C 172.16.0.0/16 is directly connected, Serial0

C 192.168.2.0/24 is directly connected, Ethernet0

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC

192.168.2.0/24

.1 .1

10.0.0.0/8

s0 s0 s1s1e0 e0


RTB#show ip route

Codes: C - connected,.. <Other codes and gateway information omitted>



RTC#show ip route

Codes: C - connected,.. <Other codes and gateway information omitted>C 10.0.0.0/8 is directly connected, Ethernet0


• The Routing Tables

– Notice that the routers only know about their own directly connected networks.

– They are not sharing routing information because we have not configured any static routes ordynamic routing protocols.



Extra: Extended Ping Command

RTA#show ip route



172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC

192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0


RTB#show ip route

Codes: C - connected,.. <Other codes and gateway information omitted>C 172.16.0.0/16 is directly connected, Serial0


RTA#ping

Protocol [ip]:

Target IP address: 172.16.0.2

Extended commands [n]: ySource address or interface: 192.168.2.1

Sending 5, 100-byte ICMP Echos to 172.16.0.2, timeout is 2 seconds:

.....

RTA#ping 172.16.0.2 source 192.168.2.1

E Li h ibl h f h Pi



Extra: Lists the possible output characters from the Pingfacility




Extra: IP Traceroute Text Characters




Cisco Discovery Protocol (CDP)

Network discovery with CDP

• CDP is an information-gathering tool used by network administrators toget information about directly connected Cisco devices.

• CDP is a proprietary tool that enables you to access a summary ofprotocol and address information about Cisco devices that are directlyconnected.

• These advertisements contain information such as the types of devices


that are connected, the router interfaces they

are connected to, the interfaces used to

make the connections, and the model

numbers of the devices.

• Concept of neighbors – 2 types of neighbors

Layer 3 neighbors

Layer 2 neighbors



Cisco Discovery Protocol (CDP)

CDP Operation

• CDP runs at the Data Link layer connecting the physical media to theupper-layer protocols (ULPs).

• Cisco network devices, such as routers that support different Networklayer protocols (for example, IP and Novell IPX), can learn about eachother

•


device: – Device identifiers

– Address list

– Port identifier

– Capabilities list

– Platform



Default Setting

Feature Default Setting

CDP global state Enabled


nter ace state na e

CDP holdtime (packet holdtime in seconds) 180

CDP timer (packets sent every x seconds) 60



Using CDP for Network Discovery

• The information gathered by the CDP protocol can beexamined with the show cdp neighbors command.





Field Definition

Device ID The name of the neighbor device and either the

MAC address or the serial number of this

device.

Local Intrfce The protocol being used by the connectivity


.

Holdtme The remaining amount of time (in seconds) thecurrent device will hold the CDP advertisement

from a sending router before discarding it.

C




Capability

(Capability

Codes)

Capability (type of routing device) of the listed

neighboring device.

The capability types that can be discovered are:

R—RouterT—Transparent bridge

B—Source-routing bridge


S—Switch

H—Host

I— device is using IGMP

r—Repeater

Platform The product number of the device.

Port ID The protocol and port number of the device.

U i CDP f N k Di





CDP C d



CDP Commands


CDP C d



CDP Commands


CDP Commands



CDP Commands




Static Routeswith “Next Hop” Addresses


Purpose and Command Syntax of ip route




• Static routes are commonly used when routing from a network toa stub network.

– A stub network is a network accessed by a single route.







Configuring Static Routes



Configuring Static Routes

• Installing a Static Route in the Routing Table


Verifying Static Route Commands



Verifying Static Route Commands

Configuring Routes to Two More Remote Networks


Routing Table Principles and Static Routes




• Applying the Principles




Resolving to an Exit Interface



Resolving to an Exit Interface

• Exit Interface is down


Extra: Static Routing – Recursive Lookups



RTA(config)#ip route 192.168.1.0 255.255.255.0 172.16.0.2

RTA#show ip route

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC

192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

Extra: Static Routing Recursive Lookups


Co es: C - connecte , S - stat c,

C 172.16.0.0/16 is directly connected, Serial0S 192.168.1.0/24 [1/0] via 172.16.0.2


12

Extra: Static Routing – Recursive Lookups



RTA(config)#ip route 10.1.0.0 255.255.0.0 192.168.1.2

RTA#show ip route

Codes: C - connected, S - static,

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC

192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

g p



S 192.168.1.0/24 [1/0] via 172.16.0.2

S 10.1.0.0/16 [1/0] via 192.168.1.2


2

3

Extra: Static Routing – Endless Recursion



• Route1: ip route 10.1.0.0 255.255.0.0 20.1.1.1

g


• Route2: ip route 20.1.0.0 255.255.0.0 30.1.1.1

• Route3: ip route 30.1.0.0 255.255.0.0 10.1.1.1



Static Routes with Exit Interface


Configuring a Static Route with an Exit Interface



• Static routes can be configured with an exit interface, whichallows the routing table to resolve the exit interface in a single

search instead of two searches.


Configuring a Static Route with an Exit Interface



• Static Route and an Exit Interface


Modifying Static Routes



• There are times when a previously configured static route needs to bemodified:

– The destination network no longer exists, and therefore the staticroute should be deleted.

– There is a change in the topology, and either the intermediateaddress or the exit interface has to be changed.


Verifying the Static Route Configuration



• Use the following commands

Step 1: show running-config

Step 2 verify static route has been entered correctly

Step 3: show ip route

Step 4 verify route was configured in routing table

Step 5 issue ping command to verify packets can reach destination


an a e urn pa s wor ng

Static Routes with Ethernet Interfaces



• Ethernet interfaces and ARP.

– If a static route is configured on an Ethernet link, if the packet issent to the next-hop router then

• the destination MAC address will be the address of the nexthop’s Ethernet interface

• This is found by the router consulting the ARP table

’


–

Static Routes with Ethernet Interfaces



Static routes and Ethernet exit interfaces

• With Ethernet networks, may be many different devices sharing

the same multi-access network so the router does not know the

next-hop IP address and it cannot determine the destinationMAC address for the Ethernet frame.


Extra: Static Routing – Ethernet interfaces



172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC

192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

RTA(config)#ip route 192.168.1.0 255.255.255.0 eth1 172.16.0.2

RTA#show ip route

e1 e0


• Static routes via point-to-point links

– It is best to configure static routes with only the exit interface.

• Static routes via broadcast networks such as Ethernet

– It is best to configure static routes with both the next-hop address

and the exit-interface.

Codes: C - connected, S - static,

C 172.16.0.0/16 is directly connected, Ethernet1S 192.168.1.0/24 [1/0] via 172.16.0.2 Ethernet1




Summary and Default Static Routes


Summary Static Routes



• Summarizing Routes to Reduce the Size of the Routing Table

• Route Summarization: Multiple static routes can be summarized into asingle static route if:

– The destination networks can be summarized into a single networkaddress, and

– The multiple static routes all use the same exit-interface or next-


Summary Static Routes



• Configuring a Summary Route:

Step 1: Delete the currentstatic route

Step 2: Configure thesummary static route


route

Host 1

172.16.1.0/24

Extra: Summarizing static routes



Hub

S0S0

S0 S1

E0

172.16.2.0/24

172.16.1.0/24

192.168.1.0/24

SanJose2

SanJose1

Baypointe

.1

.1 .1

.2.2172.16.0.0/22


• Baypointe(config)# ip route 172.16.1.0 255.255.255.0 192.168.1.2• Baypointe(config)# ip route 172.16.2.0 255.255.255.0 192.168.1.2

• Baypointe(config)# ip route 172.16.3.0 255.255.255.0 192.168.1.2

• Summarized route:

Baypointe(config)#ip route 172.16.0.0 255.255.252.0 192.168.1.2

Host 2 Host 3

Hub Hub

172.16.3.0/24 192.168.2.0/24

..

Default Static Route



• A default static route is a route that will match all packets. Default staticroutes are used:

– When no other routes in the routing table match the packet'sdestination IP address. In other words, when a more specific matchdoes not exist. A common use is when connecting a company'sedge router to the ISP network.

– When a router has only one other router to which it is connected.


This condition is known as a stub router.

Default Static Route



• Verifying a Default Static Route


Extra: Common uses for Static Routes



ISP

10.1.1.2/24

10.1.1.1/24

ip route 172.16.0.0 255.255.0.0 10.1.1.2

Default


172.16.0.0/16ip route 0.0.0.0 0.0.0.0 10.1.1.1

RTB#show ip route

Gateway of last resort is 10.1.1.1 to network 0.0.0.0


10.0.0.0/24 is subnetted, 1 subnets

C 10.1.1.0 is directly connected, Serial1

S* 0.0.0.0/0 [1/0] via 10.1.1.1



Managing and


Static Routes and Packet Forwarding



• Static Routes and Packet Forwarding






Troubleshooting a Missing Route



• Tools that can be used to isolate routing problems include:

– ping – tests end to end connectivity

– traceroute – used to discover all of the hops (routers) along

the path between 2 points – show IP route – used to display routing table & ascertain

forwarding process


– show ip interface brief - used to show status of router

interfaces

– show cdp neighbors detail – used to gather configurationinformation about directly connected neighbors

Solving the Missing Route



• Finding a missing or miss-configured route requires methodically usingthe correct tools

– Start with ping . If ping fails then use traceroute to determinewhere packets are failing to arrive

• Issue: show ip route to examine routing table.

– If there is a problem with a miss-configured static route remove the


Solving:

– R2(config)#no ip route 172.16.3.0 255.255.255.0 serial0/0/1

– R2(config)#ip route 172.16.3.0 255.255.255.0 serial 0/0/0

Basic Static Route Configuration Lab




Challenge Static Route Configuration Lab




Summary

ca ex s2m02 static routing

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